Estimated to be more than 200 years old, such milestones were used to measure distances and also served as benchmarks, officials said.

“We spoke to the heritage committee and are planning to restore the milestone, which was covered with temporary benches until now,” said Vishwas Mote, assistant commissioner, F/South ward office.

Authorities found the relic while they were taking action against 16 stalls and 20 shanties. To clear the footpath, they also towed illegally parked vehicles, said Mote.

There are about 15 grade - 1 heritage milestones in the city; though a few of them are yet to be found. A milestone can be seen near the St Thomas Cathedral near Kala Ghoda. There is one near Sion Fort and one at Kataria Marg in Mahim. The Bhau Daji Lad museum houses a few of these milestones.

Encroachments, roadworks and utility works constantly pose a threat to the relics. The civic body has not yet taken steps to restore and maintain them.

“The milestones are important as they give us an idea of what the city was like then. Such discoveries should prompt authorities to maintain these structures,” said conservation architect Vikas Dilawari.